80 COLLEMACEI. [COLLEMOPSIS. 



minute, somewhat concave, bright- or reddish-testaceous, the margin 

 thickish; spores oblong, simple or spuriously 1-septate, 0,016-30 

 mm. long, 0,006-7 mm. thick ; hymenial gelatine obsoletely bluish, 

 becoming very faintly wine-red with iodine. Cromb. Grevillea, iii. 

 p. 22 ; Leight. Lich. Fl. ed. 3, p. 36. 



At first sight this might be taken for a Lecidea belonging to the 

 Gyalectas, and only a microscopical examination makes its true relations 

 apparent. It differs from the preceding in the colour of the thallus and 

 in the spores. The apothecia are sometimes not very well developed, as 

 is not unfrequently the case with lichens growing in similar situations. 



Hal. On the ground in shady crevices of limestone rocks in upland 

 tracts. Distr. Only very sparingly in N.W. England. B. M. : Ha,ver- 

 brack Hill, Westmoreland. 



6. C. diffundens Nyl. ex Cromb. Journ. Bot. 1874, p. 332. 

 Thallus effuse, thin, areolato-squamulose, black, opaque ; squamules 

 subfurfurous, small, variable. Apothecia small, innate, somewhat 

 plane or often gyalectoid, reddish, pale within ; spores ellipsoid, 

 0,011-23 mm. long, 0,007-11 mm. thick; paraphyses slender, dis- 

 crete ; hymenial gelatine bluish, then wine-red with iodine. 

 Leight. Lich. Fl. ed. 3, p. 36. Pyrenopsis diffundens Nyl. Flora, 

 1865, p. 602; Carroll, Journ. Bot! 1866, p. 92; Cromb. Lich. Brit, 

 p. 3; Leight. Lich. Fl. p. 16. Collema diffractum Nyl. Carroll, 

 Journ. Bot. 1865, p. 287. 



The thallus and fructification sufficiently distinguish this from other 

 British species. I have not seen an authentic specimen, and the plant 

 has been vainly searched for at Maidstone, Kent, where it was originally 

 found. Specimens somewhat aberrant have been gathered elsewhere. 



Hob. On sandstone and schistose rocks. Distr. Very local and scarce 

 in S.E, England and N. Wales. B. M. : Near Barmouth, Merioneth- 

 shire. 



7. C. leptogiella Nyl. Flora, 1877, p. 220. Thallus effuse, thin, 

 minutely subcoralloideo-furfuraceous, olive-brown. Apothecia lep- 

 togioid, minute, lurid-testaceous, slightly margined, the epithe- 

 cium somewhat impressed or at length subplane ; spores ellip- 

 soid or oblongo-ellipsoid, 0,010-17 mm. long, 0,005-7 mm. thick ; 

 paraphyses slender, or somewhat slender, thicker at the apices ; 

 hymenial gelatine tawny wine-reddish with iodine. Cromb. Gre- 

 villea, vi. p. 18 ; Leight. Lich. Fl. ed. 3, p. 36. 



This peculiar species departs in various respects from the rest, and 

 belongs almost to a proper genus. The thallus is confusedly cellular, 

 with the gonimia nearly moderate. The branchlets, which resemble 

 those of Leptogium microscopicum, though shorter, are subpapilliform. 

 In the only specimen seen by me, the apothecia are fairly numerous, the 

 margin being usually very thin. 



Hab. On quartzose rocks in upland districts. Distr, Very local and 

 rare in N.W. Ireland. B. M. : Kylemore, co. Galway. 



